"We're still trying to determine what provoked these actions," Police Chief Jerry Dyer told reporters at a news conference.

The Fresno Bee said the shooter had worked at the plant for 14 months. Employees told investigators that Jones, "did not appear to be himself when he came to work." Chief Dyer said the man was more than three hours into his shift when he pulled a handgun and began shooting. An estimated 60 people were at the business at the time of the shooting.

The Fresno Bee spoke to witnesses who saw factory workers running from the plant. Roger Medina told the newspaper that he was in a nearby McDonald's when a man wearing a meat cutter's vest came rushing in.

"He said, 'There's a guy shooting people over there,' " Medina said.

Joe Martinez, 45, was in the drive-through lane at the McDonald's and thought he heard a car backfire, the newspaper reported. But he knew it was something else when he saw a chaotic scene unfolding near the plant.

"It's the last thing you expect to see," Martinez told the newspaper. "It's very upsetting."